1. Field of the Invention
The present invention relates to a zoom lens system suitable for a single-lens reflex camera using a film or a solid-state imaging device.
2. Related Background Art
There have been proposed zoom lens systems having a vibration reduction function with a zoom ratio of about four in such as Japanese Paten Application Laid-Open Nos. 8-62541 and 10-133114.
Examples disclosed in Japanese Patent Application Laid-Open No. 8-62541 are a positive-negative-positive-positive-negative five-lens-group zoom lens system or a positive-negative-positive-negative-positive-negative six-lens-group zoom lens system, in which a second lens group with negative refractive power is moved for vibration reduction.
An example disclosed in Japanese Patent
Application Laid-Open No. 10-133114 is a positive-negative-negative-positive-negative five-lens-group zoom lens system in which a portion of a fourth lens group with positive refractive power is moved for vibration reduction.
However, in any one of disclosed examples, an effective diameter of a vibration reduction lens group is large about 25 mm or more, so that a vibration reduction mechanism becomes large. Accordingly, it becomes difficult to make the zoom lens system small. Moreover, the number of lens groups of a zoom lens system is five or more, so that a zooming mechanism becomes complicated.